/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.support.v4.app;

/**
 * Static library support version of the framework's
 * {@link android.app.FragmentTransaction}. Used to write apps that run on
 * platforms prior to Android 3.0. When running on Android 3.0 or above, this
 * implementation is still used; it does not try to switch to the framework's
 * implementation. See the framework SDK documentation for a class overview.
 */
public abstract class FragmentTransaction {
	/**
	 * Calls {@link #add(int, Fragment, String)} with a 0 containerViewId.
	 */
	public abstract FragmentTransaction add(Fragment fragment, String tag);

	/**
	 * Calls {@link #add(int, Fragment, String)} with a null tag.
	 */
	public abstract FragmentTransaction add(int containerViewId, Fragment fragment);

	/**
	 * Add a fragment to the activity state. This fragment may optionally also
	 * have its view (if {@link Fragment#onCreateView Fragment.onCreateView}
	 * returns non-null) into a container view of the activity.
	 * 
	 * @param containerViewId
	 *            Optional identifier of the container this fragment is to be
	 *            placed in. If 0, it will not be placed in a container.
	 * @param fragment
	 *            The fragment to be added. This fragment must not already be
	 *            added to the activity.
	 * @param tag
	 *            Optional tag name for the fragment, to later retrieve the
	 *            fragment with
	 *            {@link FragmentManager#findFragmentByTag(String)
	 *            FragmentManager.findFragmentByTag(String)}.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction add(int containerViewId, Fragment fragment, String tag);

	/**
	 * Calls {@link #replace(int, Fragment, String)} with a null tag.
	 */
	public abstract FragmentTransaction replace(int containerViewId, Fragment fragment);

	/**
	 * Replace an existing fragment that was added to a container. This is
	 * essentially the same as calling {@link #remove(Fragment)} for all
	 * currently added fragments that were added with the same containerViewId
	 * and then {@link #add(int, Fragment, String)} with the same arguments
	 * given here.
	 * 
	 * @param containerViewId
	 *            Identifier of the container whose fragment(s) are to be
	 *            replaced.
	 * @param fragment
	 *            The new fragment to place in the container.
	 * @param tag
	 *            Optional tag name for the fragment, to later retrieve the
	 *            fragment with
	 *            {@link FragmentManager#findFragmentByTag(String)
	 *            FragmentManager.findFragmentByTag(String)}.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction replace(int containerViewId, Fragment fragment, String tag);

	/**
	 * Remove an existing fragment. If it was added to a container, its view is
	 * also removed from that container.
	 * 
	 * @param fragment
	 *            The fragment to be removed.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction remove(Fragment fragment);

	/**
	 * Hides an existing fragment. This is only relevant for fragments whose
	 * views have been added to a container, as this will cause the view to be
	 * hidden.
	 * 
	 * @param fragment
	 *            The fragment to be hidden.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction hide(Fragment fragment);

	/**
	 * Shows a previously hidden fragment. This is only relevant for fragments
	 * whose views have been added to a container, as this will cause the view
	 * to be shown.
	 * 
	 * @param fragment
	 *            The fragment to be shown.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction show(Fragment fragment);

	/**
	 * Detach the given fragment from the UI. This is the same state as when it
	 * is put on the back stack: the fragment is removed from the UI, however
	 * its state is still being actively managed by the fragment manager. When
	 * going into this state its view hierarchy is destroyed.
	 * 
	 * @param fragment
	 *            The fragment to be detached.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction detach(Fragment fragment);

	/**
	 * Re-attach a fragment after it had previously been deatched from the UI
	 * with {@link #detach(Fragment)}. This causes its view hierarchy to be
	 * re-created, attached to the UI, and displayed.
	 * 
	 * @param fragment
	 *            The fragment to be attached.
	 * 
	 * @return Returns the same FragmentTransaction instance.
	 */
	public abstract FragmentTransaction attach(Fragment fragment);

	/**
	 * @return <code>true</code> if this transaction contains no operations,
	 *         <code>false</code> otherwise.
	 */
	public abstract boolean isEmpty();

	/**
	 * Bit mask that is set for all enter transitions.
	 */
	public static final int TRANSIT_ENTER_MASK = 0x1000;

	/**
	 * Bit mask that is set for all exit transitions.
	 */
	public static final int TRANSIT_EXIT_MASK = 0x2000;

	/** Not set up for a transition. */
	public static final int TRANSIT_UNSET = -1;
	/** No animation for transition. */
	public static final int TRANSIT_NONE = 0;
	/** Fragment is being added onto the stack */
	public static final int TRANSIT_FRAGMENT_OPEN = 1 | TRANSIT_ENTER_MASK;
	/** Fragment is being removed from the stack */
	public static final int TRANSIT_FRAGMENT_CLOSE = 2 | TRANSIT_EXIT_MASK;
	/**
	 * Fragment should simply fade in or out; that is, no strong navigation
	 * associated with it except that it is appearing or disappearing for some
	 * reason.
	 */
	public static final int TRANSIT_FRAGMENT_FADE = 3 | TRANSIT_ENTER_MASK;

	/**
	 * Set specific animation resources to run for the fragments that are
	 * entering and exiting in this transaction. These animations will not be
	 * played when popping the back stack.
	 */
	public abstract FragmentTransaction setCustomAnimations(int enter, int exit);

	/**
	 * Set specific animation resources to run for the fragments that are
	 * entering and exiting in this transaction. The <code>popEnter</code> and
	 * <code>popExit</code> animations will be played for enter/exit operations
	 * specifically when popping the back stack.
	 */
	public abstract FragmentTransaction setCustomAnimations(int enter, int exit, int popEnter, int popExit);

	/**
	 * Select a standard transition animation for this transaction. May be one
	 * of {@link #TRANSIT_NONE}, {@link #TRANSIT_FRAGMENT_OPEN}, or
	 * {@link #TRANSIT_FRAGMENT_CLOSE}
	 */
	public abstract FragmentTransaction setTransition(int transit);

	/**
	 * Set a custom style resource that will be used for resolving transit
	 * animations.
	 */
	public abstract FragmentTransaction setTransitionStyle(int styleRes);

	/**
	 * Add this transaction to the back stack. This means that the transaction
	 * will be remembered after it is committed, and will reverse its operation
	 * when later popped off the stack.
	 * 
	 * @param name
	 *            An optional name for this back stack state, or null.
	 */
	public abstract FragmentTransaction addToBackStack(String name);

	/**
	 * Returns true if this FragmentTransaction is allowed to be added to the
	 * back stack. If this method would return false,
	 * {@link #addToBackStack(String)} will throw {@link IllegalStateException}.
	 * 
	 * @return True if {@link #addToBackStack(String)} is permitted on this
	 *         transaction.
	 */
	public abstract boolean isAddToBackStackAllowed();

	/**
	 * Disallow calls to {@link #addToBackStack(String)}. Any future calls to
	 * addToBackStack will throw {@link IllegalStateException}. If
	 * addToBackStack has already been called, this method will throw
	 * IllegalStateException.
	 */
	public abstract FragmentTransaction disallowAddToBackStack();

	/**
	 * Set the full title to show as a bread crumb when this transaction is on
	 * the back stack.
	 * 
	 * @param res
	 *            A string resource containing the title.
	 */
	public abstract FragmentTransaction setBreadCrumbTitle(int res);

	/**
	 * Like {@link #setBreadCrumbTitle(int)} but taking a raw string; this
	 * method is <em>not</em> recommended, as the string can not be changed
	 * later if the locale changes.
	 */
	public abstract FragmentTransaction setBreadCrumbTitle(CharSequence text);

	/**
	 * Set the short title to show as a bread crumb when this transaction is on
	 * the back stack.
	 * 
	 * @param res
	 *            A string resource containing the title.
	 */
	public abstract FragmentTransaction setBreadCrumbShortTitle(int res);

	/**
	 * Like {@link #setBreadCrumbShortTitle(int)} but taking a raw string; this
	 * method is <em>not</em> recommended, as the string can not be changed
	 * later if the locale changes.
	 */
	public abstract FragmentTransaction setBreadCrumbShortTitle(CharSequence text);

	/**
	 * Schedules a commit of this transaction. The commit does not happen
	 * immediately; it will be scheduled as work on the main thread to be done
	 * the next time that thread is ready.
	 * 
	 * <p class="note">
	 * A transaction can only be committed with this method prior to its
	 * containing activity saving its state. If the commit is attempted after
	 * that point, an exception will be thrown. This is because the state after
	 * the commit can be lost if the activity needs to be restored from its
	 * state. See {@link #commitAllowingStateLoss()} for situations where it may
	 * be okay to lose the commit.
	 * </p>
	 * 
	 * @return Returns the identifier of this transaction's back stack entry, if
	 *         {@link #addToBackStack(String)} had been called. Otherwise,
	 *         returns a negative number.
	 */
	public abstract int commit();

	/**
	 * Like {@link #commit} but allows the commit to be executed after an
	 * activity's state is saved. This is dangerous because the commit can be
	 * lost if the activity needs to later be restored from its state, so this
	 * should only be used for cases where it is okay for the UI state to change
	 * unexpectedly on the user.
	 */
	public abstract int commitAllowingStateLoss();
}
